ALEXANDRIA, Va. — A judge ordered jurors Friday to keep deliberating after they said they were deadlocked in a lawsuit alleging a Virginia-based military contractor is liable for abuses suffered by inmates at the Abu Ghraib prion in Iraq two decades ago.

The eight-person civil jury has deliberated the equivalent of three full days in the civil suit in U.S. District Court in Alexandria.

The trial , which began April 15, is the first time a U.S. jury has heard claims of mistreatment brought by survivors of Abu Ghraib.

Three former detainees sued Reston, Virginia-based contractor CACI. They allege the company is liable for the mistreatment they suffered when they were imprisoned at Abu Ghraib in 2003 and 2004 after the U.S. invasion of Iraq.

CACI supplied civilian contractors to work at Abu Ghraib as interrogators, in support of shorthanded U.S. Army soldiers. Abuse of detainees at Abu Ghraib became a worldwide scandal 20 years ago when photos became public showing U.S. soldiers smiling and laughing as they inflicted physical and sexual abuse on detainees in shockingly graphic ways.

The plaintiffs have argued at trial that CACI interrogators contributed to their mistreatment, even if they didn't commit the abuses themselves, by conspiring with soldiers to mistreat inmates as a way to “soften them up” for questioning.

On Friday, the jury sent out a note saying that they have extensively discussed the evidence but “we are still not unanimous on anything.”

As is typical when a jury sends out such a note, U.S. District Judge Leonie Brinkema told the jurors they must continue their deliberations. She sent them home early Friday afternoon to resume deliberating Monday morning.

During deliberations this week, the jury asked multiple questions about how to apply a legal principle known as the “borrowed servants” doctrine.

CACI, as one of its defenses, has argued it shouldn't be liable for any misdeeds by its employees if they were under the control and direction of the Army.

The plaintiffs' lawyers tried to bar CACI from making that argument at trial, but Brinkema allowed the jury to consider it.

Both sides have argued about scope of the doctrine. Fundamentally, though, if CACI has proven that its interrogators were under the command and control of the Army at the time any misconduct occurred, then the jury has been instructed to find in favor of CACI.

The issue of who controlled CACI interrogators occupied a significant portion of the trial. CACI officials testified that they basically turned over supervision of the interrogators to the Army.

Lawyers for the plaintiffs argued otherwise, and introduced evidence including CACI’s contract with the Army, which required CACI to supervise its own employees. Jurors also saw a section of the Army Field Manual that pertains to contractors and states that “only contractors may supervise and give direction to their employees.

The trial and the jury's deliberations come after legal wrangling and questions over whther CACI could be sued resulted in more than 15 years of legal wrangling.